1. Field of the Invention
This invention relates generally to an apparatus for generating an image according to an ultrasonic wave. In particular, this invention relates to an ultrasound apparatus for medical examinations of a patient. Still more particularly, this invention relates to an ultrasonic apparatus containing an ultrasonic wave-generating transducer for providing ultrasonic waves to insonify an object under observation, and an ultrasonic receiving transducer for converting at least a portion of an acoustic image field received from the object into electrical signals. The ultrasonic apparatus works in the transmission mode.
2. Description of the Prior Art
Ultrasonic systems of the type herein contemplated are disclosed, for instance, in U.S. Pat. No. 3,937,066, in Acoustical Holography, Vol. 5, pages 493-503, 1974, and in Acoustical Holography, Vol. 6, pages 1-13, 1976.
In the transmission mode C-scan ultrasonic systems according to the prior art, components such as the ultrasonic wave-generating transducer, the focusing lens, the scanning device, and the ultrasonic receiving transducer are arranged on the same axis. The prior art systems as a rule include as the scanning device a deflector assembly comprising a pair of acoustic prisms rotated in opposite rotational directions at the same speed. Due to the on-axis-arrangement, the whole system is usually very lengthy, and space problems may exist with respect to the placement in an examination room. Frequently a water tank is used between the emitting transducer and the receiving transducer. For examination purposes, the patient must enter the water tank. This is inconvenient especially for elderly patients. In addition, the prior art ultrasound systems generally do not provide for any clearance for non-observed organs of the patient. Therefore, in particular breast examinations are difficult to perform. Also, in a typical prior art ultrasonic system examinations of the breast in different directions are only possible if the patient herself moves into various positions. The system itself is stationary so that precise directional examinations are difficult to make.